Engine starter gearing



Filed. Sept. 21, 195.8

2 Sheets-Sheet l INVENTOR.

Si n; 5m

flwwydflw M W ATTORNEY.

P 3, 1940- Y. S EKELLA 2,213,934

ENGINE STARTER GEARING Filed Sept. 21, 1938 2 Sheets-Sheet 2 Patented Sept. 3, 1940 ENGINE STARTER Gamma Youston Sekella, Heights, N. r., minorto Bendix Aviation Corporation, South Bend, Ind., a corporation of Delaware Application September 21, 1938, Serial No. 231,010

14 Claims.

The present invention relates to engine starter gearing and more particularly to a yielding drive for automatically connecting and disconnecting a starting motor and a member of an engine to be start g It is an object of the present invention to provide a novel starter drive which is eflicient and reliable in operation and simple and economical inconstruction.

It is another object to provide such a device which is small and compact in comparison with existing drives of comparable torque capacity.

It' is a further object to provide such a device comprising a yielding element which is arranged to surround the parts of the drive which provide relative longitudinal movement of the engine driving member, which parts are thus nested in the yielding element.

It is another object to provide such a device in which the yielding element is subjected to simple compression during the driving operation, the rotary component of the driving forces being transmitted by a positive mechanical connection.

It is another object to providesuch a device including arrangements for preventing the pinion from drifting or rebounding into undesired engagement with the engine member. r

It is a further object to provide such a device which may be arranged so that the engine driving member engages the member of the engine to be driven by motion away from the starting motor, but which is so designed as to render unnecesssgraytany outboard bearing for the starting motor Further objects and advantages will be apparent from the following description taken in connection with the accompanying drawings in which:

Fig. 1 is a side elevation partly in section of one preferred embodiment of the invention;

. Fig. 2 is a section taken substantiaully on the Fig. 6 is'a view similar to Fig. 4 showing'the parts in operative or cranking position; and

Fig. 7 is a detail in perspective of the transmission element comprising the screw shaft and aeeve illustrated in Figs. 4 and 6. In'Fig. 1 of the drawings, there is illustrated l apower shaft I which maybe the extended armature shaft of a starting motor 2, on the outer end of which is rigidly mounted a screw shaft 3 by suitable means such as a key 4 and set screw 5. A pinion member 5 is slidably journalled on the power shaft l for movement into 5 and out of engagement with a member such as a flywheel gear 'Iof an engine to be started. The pinion member 6 comprises an extended hub 8 on which is suitably fixed as by welding or brazing a thrust member 9 which is ar- 10 ranged to engage the end of the screw shaft 3 when the pinion is in operative engagement with the flywheel gear I, and thus define said operative position.

A nut member II is threaded on the screw shaft 3, and a barrel member i2 is arranged to surround the 'nut member and. screw shaft and isrigidly connected at one end to the thrust member 9 of the pinion as by means of radial projections I 3 on the thrust member engaging 20 in slots M in the barrel and retained therein by means ofasplitlockring i5. v

The nut II is provided with radial projections l6 at one end which extend through the slots 4 of the barrel and thereby provide a splined 25 connection between the nut and barrel. 'The ber9.

The yielding thrust member l9 and its asso ciated parts are preferably enclosed by suitable 40 means such as a shell 2| mounted over the flange II and thrustring l8 and retained thereon in any suitable way as 'by means of a split 'ring 22. Means for preventing foreign material such as rubber dust from entering the threads of the screw shaft and nut are preferably provided in the form of a sheet. metal thimble 23 slidably mounted on the barrel and having a radial flange 24 interposed between the thrust ring l8 and the projections l6 of the nut.

Means are provided for preventing the pinion member 6 from drifting into engagement with the flywheel gear I in the form of a spring 25 mounted on the power shaft" I between the pinion ember and screw shaft.

In order to prevent the pinion member from rebounding into engagement with the flywheel gear after being demeshed therefrom, the nut member H is threaded for only a portion of its length, leaving a smooth counterbore 26 so that the nut Ii may run oh the ends of the threads on the screw shaft and permit the nut with its associated parts to overrun'the screw shaft until their rotational energy is disipated. Means are provided for insuring initial reengagement of the threads of the pinion and screw shaft in the form of a re-entry spring 21 on the screw shaft abutting the ends of the threads thereof preferably by means of a thrust ring 28, and engaging at its other end with a thimble 29 having a. radial flange 3| in abutting relation with the flange I! of the barrel and maintained thereagainst by an inturned flange 32 on the end of the shell 25..

In the operation of this embodiment of the invention, rotation of the power shaft in the direction of the arrow in Fig. 1 causes the nut H to thread itself onto the screw shaft 3, drawing the barrel l2 and its associated elements including the pinion member 6 to the left in Fig. 1 until the pinion is fully meshed with the engine gear I and the thrust element 9 engages the adjacent end of the screw shaft 3. The longitudinal motion of the pinion member, barrel and associated parts is thus arrested, and further rotation of the screw shaft causes the nut H to compress the thrust block l9, while applying increasing torque to the barrel 12 through the spline projections l6 untilthe resistance of the engine gear I to rotation is overcome. The parts of the drive thereupon rotate substantially in unison, the yielding thrust block 3- acting as a cushion to form a yielding. driving connection.

, When the engine starts, the acceleration of the pinion member 6 by the engine gear is transmitted through the barrel l2 to nut ll, causing it to overrun the screw shaft and thread itself and its associated parts back to idle position.

If during the meshing operation a tooth of the pinion engages the end of a tooth of the flywheel gear so as to obstruct the meshing movement of the pinion, the'longitudinal movement of the nut ll continues, compressing the thrust block l9 until sufiicie'nt torque is built up to' cause the pinion to be indexed into proper registry with the tooth spaces of the engine gear. The block I!) thereupon expands, snapping the pinion B into initial mesh which is completed and the driving operation instituted in the usual manner.

vIn the embodiment of the invention illustrated in Figs. 4 to '7, a power shaft is provided with a smooth portion 42, a splined portion 43 and a reduced smooth portion 44. A pinion member 45- is slidably journalled on the smooth portion 42 of the power shaft for longitudinal movement a pin ,49.

A- barrel member 5| surrounding the screw shaft and nut is rigidly connected to the pinion 45 so as to be substantially a part thereof preferably as by means of a welded or brazed connection 52. An abutment member. 53 slidably bearing on the sleeve "is fixed in the free end of the barrel 5| by suitable means such as radial lugs 54 engaging in slots 55 in the barrel and retained therein by means of a split lock ring 55. The thrust member 53 is arranged to engage the screw shaft 66 to thereby determine the operative position of the pinion and associated parts on the power shaft.

A nut 51 is threaded on the screw shaft 58 and is provided with radial projections 58 extending through the slots 55 of the barrel 5! to form a splined connection between the nut and barrel. Thrust rings 59 and BI are mounted on the barrel 5i, ring 59 being arranged to abut against a shoulderGZ of the barrel, and ring 6! being in abutting relation to the projections 53 of nut 51 The shoulder 62 may preferably be formed byflats milled on the surface of the barrel, and the thrust rings 59 and El may have openings conforming to the flattened contour of the barrel. A cylindrical thrust block 63 of rubber or simi lar material is arranged to surround the barrel between the thrust rings 59 and ti, cooperating therewith to provide yielding means for maintaining the nut in extended relation with respect to the barrel. A protective shell 64 may be provided as indicated for enclosing the yielding thrust member, and a thimble 65 is preferably employed to prevent localized stresses in the thrust block 63, and to close the slots 55 of the barrel-adjacent the thrust block to thereby prevent entry of foreign matter into the threads of the screw shaft and nut.

An anti-drift spring 66 is mounted on the sleeve 41, hearing against the screw shaft 46 and thrust In the operation of this embodiment of the in vention, starting with the parts in their idle positions as illustrated in Fig. 4, rotation of the power shaft 4! causes the nut 5! to thread itself along the screw shaft 45 to the left in Fig. 4. The pinion, barrel member and associated parts are thereby moved along the power shaft until the pinion is meshed with the engine 4, at which time longitudinal movement of pinion is arrested by abutment of the thrust I member 53 against the screw shaft 66. .Further rotation of the screw shaft causes the nut ii? to compress the'thrust block 63, at the same time applying an increasing torque to the pinion through the splined connection 55, 58 until the resistance to rotation of the engine gear is overcome.

Proper meshing of the pinion 55 with the engine gear 40 is insured by the longitudinal elasticity of the thrust block 63 in the same manner as by the thrust block is in the embodiment of the invention first described.

When the engine starts, the acceleration of the pinion causes the nut 51'! to overrun the screw shaft. and thread itself back to idle po= sition; thus withdrawing the pinion from mesh, after which the parts overrun the screw shaft until their kinetic energy is dissipated. Thereafter the reentry spring 61- causes initial engagement of the nut 5'11 with the threads of the screw shaft while the parts are yieldingly maintained in idle position by means of the antidrift spring Bl.

Although but two embodiments of the inven, tion have been shown and described in detail, it will be understood that other embodiments are possible and various changes may be made in the design and arrangements of the parts without departing from the spirit of 'the invention as defined in the claims appended hereto.

What is claimed is:

1. In an engine starter drive, a power shaft, a screw shaft fixed thereon, a nut member on the'screw shaft, a barrel splined on the nut, a pinion slidably journalled on the power shaft rigidly connected to one end of the barrel, the pinion and barrel assembly having abutment means, normally bearing against the end of the nut andarranged to abut against the end of the screw shaft for limiting the engaging movement of the pinion, said nut having its spline member projecting through the barrel, and means including an elastically compressible memberseated on the barrel cooperating with said'spline members for limiting the relative longitudinal movement of the nut and barrel to form a yielding driving connection for rotating the barrel and pinion from the screw shaft.

2. In an engine starter drive, a power shaft, a screw shaft fixed thereom-a nut member threaded on the screw shaft, a slotted barrel slidably mounted on the nut having a radial flange at one end, a. pinion slidably journalled on the power shaft rigidly connected to the opposite end of the barrel, the pinion and barrel assemblyhaving means for engaging the screw shaft for limiting the engaging movement of the pinion, said nut having spline members projecting through the slots of the barrel, and means including an elastically compressible member seated on the barrel against said flan e cooperating with said splines for limiting the relative longitudinal movement of the nut and barrel.

3. In an engine starter drive, a power shaft, a screw shaft fixed thereon, a nut member threaded on the screw shaft, a slotted barrel slidably mounted on the nut having a radial flange at one end, a pinion slidably journalled on the power shaft rigidly connected to the barrel, the

pinion and barrel assembly having means for engagin the screw shaft for limiting theengaging movement of the pinion, said nut having spline members projecting through the slots of the barrel, a thrust member loosely mounted on the barrel in, abutting relation with the spline members, and an annulus of elastically deformable material on the barrel between the flange and thrust member.

4. In an engine starter drive, a power shaft, a screw shaft fixed thereon, a partially threaded nut member on the screw shaft, a slotted barrel slidably mounted onthe nut, a pinion'slidably Journalled on the power shaft rigidly connected to one end of the barrel, means including a thrust block of elastically compressible material on the barrel for yieldingly resisting longitudinal movement of the nut in the barrel, yielding means urging the pinion away from the screw shaft,

- and yielding means moving the nut into initial threaded engagement with the screw shaft.

5. In an engine starter drive, a power shaft, a screw shaft fixed thereto, a pinion member journailed on--the power shaft and movable longitudinally thereon into and out of engagement with a member of an engin to be Started, Sa pinion extended hub arranged to abut the screw shaft when the pinion is engaged with the engine member, a nut threaded on the screw shaft in abutting relation to the pinion member, a barrel splined on the nut and fixed to the pinion member, and yielding means limiting relative longitudinal movement of the nut and barrel.

6. In an engine starter drive, a power shaft, a

screw shaft fixed thereto, a pinion member journailed on the power shaft and movable longituat the other end to the pinion member, said nut having spline members projecting through the slots of the barrel, and a compressible element. on the barrel between the flange and spline mem- 'bers yieldingly resisting telescoping movement of the barrel and nut member.

'7. In combination with an engine starting motor having an extended armature shaft, a screw shaft fixed adjacent the end of the armature shaft, a pinion member Journalled on the armature shaft and slidable thereon 'toward the screw shaft to engage a member of an engine to be started, a nut threaded on the screw shaft,

means positively connecting the nut and pinion for rotation in unison with freedom for relative longitudinal movement, and yielding means for transmitting longitudinal movement of the I nut to the pinion member.

8. In combination with an engine startingmotor having an extended armature shaft, a screw shaft fixed adjacent the end of the armatureshaft, a pinion member journalled on the armature shaft and slidable thereon toward the screw shaft to engage a member of an engine to be started, a nut threaded on the screw shaft,

means positively connecting the nut and pinion for rotation in unison with freedom for relative longitudinal movement, and means including an annulus of compressible material surrounding the nut for yieldably transmitting longitudinal movement of the nut to the pinion member.

9. In combination with an engine starting motor having an extended armature shaft, a screw shaft fixed adjacent the end of the armature shaft, a pinion member iournalled on the armature shaft and slidable thereon toward the screw shaft to engage a member of an engine to be started, a partially threaded nut on the screw shaft, means positively connecting the nut and pinion for rotation in unison with freedom for relative longitudinal movement, means including a yielding element encircling the nut for trans mitting longitudinal movement of the nut to the I pinion member to mesh the pinion,'said nut being arranged to run oi! the threads of the screw shaft when the pinion is demeshed, housing means for the yielding element, and means cooperating with the housing means for yieldingly urging the 'nut into threaded engagement with the screw shaft. 4

10.111 an engine starter, a power shaft, a screw shaft fixed thereto, transmission means including a pinion journalled on the power shaft and slidable into abutting relation with the screw BIS shaft to thereby operatively engage a member of an engine to be started, a nut threaded on y .the screw shaft normally in abutting relation with the transmission means, means positively connecting the nut and transmission means for rotation in unison with freedom for relative longitudinal movement, and means including a compressible member forming a connection between the nut and transmission means for moving the pinion into mesh with the engine member and thereafter cooperating with the nut to form a yielding driving connection between the screw shaft and the pinion.

11. In an engine starter drive, a power shaft, a screw shaft fixed thereon, a pinion slidably journalled on the power shaft, a nut threaded on the .screw shaft, a barrel member fixed to the pinion enclosing the screw shaft and nut and splined to the nut, a thrustv member rigidly connected. to the barrel adapted to engage the screw shaft for positively limiting longitudinal movement of the barrel with respect to the screw shaft, and means including a yielding element surrounding the barrel limiting longitudinal movement of the nut in the barrel.

12. In an engine starter drive, a power shaft having a smooth portion, a splined portion and a reduced portion, a pinion slidably journalled on thesmooth portion, a screw shaft non-rotat ably mounted on the splined portion and a sleeve rigidly connected to the screw shaft fixed on the reduced portion, a barrel member enclosing the screw shaft, rigidly connected to the pinion and having a thrust member slidable on said sleeve into abutting relation with the screw shaft, a nut splined in the barrel member, and yielding means resisting longitudinal movement of the nut in the barrel member.

13. In an engine starter drive, a power shaft, a screw shaft fixed thereon, a nut threaded on the screw shaft, 2. barrel member slidably mounted on the nut, a pinion slidably mounted on the power shaft and movable by the barrel into and out of engagement with a member of the engine to be started, means including an elastically compressible element surrounding the barrel for limiting the longitudinal movement of the nut in the barred, and a thrust member in the barrel rigidly connected to the barrel and pinion and adapted to engage the screw shaft to limit the longitudinal movement of the barrel and pinion.

14. In an engine starter drive, a power shaft, a screw shaft fixed thereon, a nut threaded on the screw shaft, a barrel member slidably mounted on the nut, a pinion slidably mounted on the power shaft and movable by the barrel into and out of engagement with a member of the englue to be started, said barrel having a radial flange at one end and having a plurality of iongitudinal slots adjacent the other end, said nut having radial lugs extending through the slots to spline the barrel to the nut, means including an elastically compressible element surrounding the barrel between the flange and said lugs for limiting the longitudinal movement of the nut in the barrel, and a thrust ring in the barrel rigidly connected to the barrel and pinion and adapted to engage the end of the screw shaft to limit the longitudinal movement of the barrel and pinion.

YOUSTON SEKELLA. 

